The present invention relates to a digital interpolator for determining a value between two known points by digital proportional division technique.
Heretofore, when a program memory, such as a read-only memory (ROM), of a limited capacity is used with an output of the ROM being f(X) for an address X of the ROM, it is often desired to determine by interpolation the f(X) for a value X which is between X.sub.1 and X.sub.2, with f(X.sub.1) and f(X.sub.2) being known values. In such a case, the f(X) may be derived from the arithmetic operation of ##EQU1## Since the operation includes a multiplication operation as well as a division operation, the operation speed is slow and the circuit configuration becomes complex because a number of adders, accumulators, registers, etc. are required.